7.3.2 Cardiac Cycle

• The cardiac cycle is the complete sequence of events that occur during one heartbeat
• During diastole, atrial and ventricular pressure are low.
• During systole, atrial pressure remains low while ventricular pressure increases dramatically
• The cardiac cycle consists of two main phases: diastole and systole.
• Stages of the cardiac cycle in order

  1️⃣ Atrial systole

  2️⃣ Ventricular systole

  3️⃣ Diastole
• During atrial systole, atrial pressure increases briefly while ventricular pressure remains low
• During ventricular systole, blood is forced into the aorta and pulmonary artery.
• The atrioventricular valves include the mitral valve on the left and the tricuspid valve on the right
• The semilunar valves prevent blood from flowing back into the ventricles during diastole.
• Match the valve type with its function:

  Atrioventricular Valves ↔️ Prevent backflow into atria

  Semilunar Valves ↔️ Prevent backflow into ventricles
• The sinoatrial (SA) node acts as the natural pacemaker
• Sympathetic nerves decrease heart rate and contractility.

  False
• Epinephrine and norepinephrine are hormones that increase heart rate and force of contraction